In the related art, a risk acquisition device is known which detects a movable object in the vicinity of the host-vehicle, determines the possibility of collision of the movable object and the host-vehicle, and outputs the possibility of collision as the degree of risk. As a technique using the risk acquisition device, for example, a collision prevention device is known.
For example, Patent Document 1 (JP2009-20745A) describes a collision prevention device which calculates a plurality of possible routes of the host-vehicle and another vehicle in the vicinity of the host-vehicle on the basis of the traveling states of the host-vehicle and another vehicle, and calculates the best host-vehicle route collision probability (host-vehicle risk) on the basis of the routes. Further, in this collision prevention device, the best host-vehicle route collision probability (offset risk) is calculated on the basis of the possible route of the host-vehicle and the possible route of another vehicle which are calculated on the basis of the offset traveling state of the host-vehicle, which is offset from the traveling state of the host-vehicle.